Substrate, solar cell including the substrate, and method of manufacturing the same

ABSTRACT

A substrate includes a semiconductor layer, a plurality of dielectric layers disposed on one side of the semiconductor layer and separated from each other and a photoactive layer disposed between the dielectric layers and including a compound of a Group III element and a Group V element. Also disclosed are a solar cell including the same and a manufacturing method thereof.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Korean Patent Application No.10-2010-0096384, filed on Oct. 4, 2010, and all the benefits accruingtherefrom under 35 U.S.C. §119, the content of which in its entirety isherein incorporated by reference.

BACKGROUND

1) Field

This disclosure relates to a substrate, a solar cell including thesubstrate and a method of manufacturing the same.

2) Description of the Related Art

A solar cell transforms solar energy into electrical energy. Typically,solar cells are diodes formed of PN junctions and they are divided intodiverse types according to a material used in a photoactive layer.

Some types of solar cells are a silicon solar cell, which includessilicon as a photoactive layer, a compound thin film solar cell, whichincludes CuInGaSe₂ (“CIGS”), CuInSe₂ (“CIS”) or CuGaSe₂ (“CGS”) as aphotoactive layer, a Group III-V solar cell, a dye-sensitive solar celland an organic solar cell.

Currently, much research into improvement of efficiency and productivityof solar cells is being actively undertaken.

SUMMARY

One aspect of this disclosure provides a substrate capable of decreasingstrain and defects of a photoactive layer and a solar cell including thesubstrate.

Another aspect of this disclosure provides a method for manufacturingthe substrate and the solar cell.

According to one aspect of this disclosure, a substrate is provided thatincludes a semiconductor layer, a plurality of dielectric layersdisposed on one side of the semiconductor layer and separated from eachother and a photoactive layer disposed between the dielectric layers andincluding a compound of a Group III element and a Group V element.

In an embodiment, the semiconductor layer may at least include Si, Geand a combination thereof. In an embodiment, the semiconductor layer mayinclude Si.

In an embodiment, the dielectric layers may include at least an oxide, anitride, an oxynitride, and a combination thereof, wherein the oxide mayinclude at least aluminum oxide (Al₂O₃), silicon oxide (SiO_(x)),titanium oxide (TiO₂ or TiO₄), and a combination thereof, the nitridemay include at least aluminum nitride (AlN), silicon nitride (SiN_(x)),titanium nitride (TiN), and a combination thereof, and the oxynitridemay include at least aluminum oxynitride (AlON), silicon oxynitride(SiON), titanium oxynitride (TiON), and a combination thereof.

In an embodiment, a distance between the dielectric layers may be fromabout 1 millimeter (mm) to about 10 mm, a thickness of the dielectriclayers may be from about 1 micrometer (μm) to about 20 μm and a width ofthe dielectric layers may be from about 1 μm to about 200 μm.

In an embodiment, the photoactive layer may include a compound of aGroup III element and a Group V element, wherein the Group III elementmay include at least B, Al, Ga, In, Tl and a combination thereof, andthe Group V element may include at least N, P, As, Sb, Bi and acombination thereof.

In an embodiment, a thickness of the photoactive layer may be equal toor less than a thickness of the dielectric layer of the plurality ofdielectric layers.

In an embodiment, the substrate may further include at least one ofauxiliary layers formed on the one side of the semiconductor layer andcovered with the photoactive layer.

In an embodiment, the auxiliary layer may include at least an oxide, anitride, an oxynitride, and a combination thereof, and the oxide, thenitride, and the oxynitride are as described above.

In an embodiment, two or more auxiliary layers are included and adistance between the auxiliary layers may be from about 10 nanometers(nm) to about 1 μm, a thickness of the auxiliary layers may be fromabout 1 nm to about 100 nm, and a width may the auxiliary layers be fromabout 1 nm to about 100 nm and the auxiliary layers are separated fromeach other.

According to another aspect of this disclosure, a method formanufacturing a substrate is provided that includes forming asemiconductor layer, forming a plurality of dielectric layers separatedfrom each other on one side of the semiconductor layer and forming aphotoactive layer including a compound of a Group III element and aGroup V element between the dielectric layers.

In an embodiment, the forming of a plurality of dielectric layers mayinclude applying a dielectric material on the one side of thesemiconductor layer and patterning the applied dielectric material.

In an embodiment, the dielectric layers may be formed such that adistance therebetween may be from about 1 mm to 10 mm, a thickness maybe from about 1 μm to 20 μm and a width may be from about 1 μm to 200μm.

In an embodiment, the photoactive layer may be formed such that athickness of the photoactive layer may be equal to or less than athickness of the dielectric layer of the plurality of dielectric layers.

In an embodiment, the method may further include forming at least two ofauxiliary layers separated from each other between the dielectriclayers, before forming the photoactive layer, and one of the auxiliarylayers may be formed such that a thickness thereof may be less than athickness of the dielectric layer.

According to yet another aspect of this disclosure, a solar cell isprovided that includes a semiconductor layer, a plurality of dielectriclayers disposed on one side of the semiconductor layer and separatedfrom each other, a photoactive layer disposed between the dielectriclayers and including a compound of a Group III element and a Group Velement, a first electrode electrically connected to the semiconductorlayer and a second electrode electrically connected to the photoactivelayer.

In an embodiment, the semiconductor layer, the dielectric layer, theGroup III element, the Group V element and the photoactive layer are asdescribed above.

In an embodiment, the second electrode may be disposed at least on oneside of the dielectric layer, on one side of the photoactive layer or onboth.

In an embodiment, when the second electrode is disposed on the one sideof the dielectric layer, a width of the second electrode may be largerthan a width of the dielectric layer of the plurality of dielectriclayers.

In an embodiment, the solar cell may further include at least two ofauxiliary layers formed between the dielectric layers, covered with thephotoactive layer and separated from each other. The auxiliary layer isas described above.

In an embodiment, the solar cell may be divided into a plurality of unitcells.

According to yet another aspect of this disclosure, a method formanufacturing a solar cell is provided that includes forming asemiconductor layer, forming a plurality of dielectric layers separatedfrom each other on one side of the semiconductor layer, forming aphotoactive layer including a compound of Group III element and a GroupV element between the dielectric layers, forming a first electrodeelectrically connected to the semiconductor layer and forming a secondelectrode electrically connected to the photoactive layer.

In an embodiment, the forming of a plurality of dielectric layers andthe formed dielectric layers are as described above.

In an embodiment, the photoactive layer may be formed such that athickness of the photoactive layer may be equal to or less than athickness of the dielectric layer of the plurality of dielectric layers.

In an embodiment, the second electrode may be disposed at least on oneside of the dielectric layer of the plurality of dielectric layers, onone side of the photoactive layer or on both.

In an embodiment, when the second electrode is disposed on the one sideof the photoactive layer, the method may further include cutting thedielectric layer of the plurality of dielectric layers, thesemiconductor layer and the first electrode along a vertical directionof the dielectric layer of plurality of dielectric layers, afterdisposing the second electrode.

In an embodiment, the method may further include forming at least two ofauxiliary layers separated from each other between the dielectriclayers, before the forming of the photoactive layer and the auxiliarylayers may be formed such that a thickness of each auxiliary layer maybe less than a thickness of the dielectric layer of the plurality ofdielectric layers.

Other aspects of this disclosure will be described in the followingdetailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, advantages and features of this disclosurewill become more apparent by describing in further detail embodimentsthereof with reference to the accompanying drawings, in which:

FIG. 1 is a cross-sectional view of an embodiment of a substrate;

FIGS. 2A to 2D are cross-sectional views sequentially showing anembodiment of a manufacturing method of the substrate;

FIG. 3A is a cross-sectional view of an embodiment of a solar cell;

FIG. 3B is a cross-sectional view of an embodiment of a unit cell of thesolar cell;

FIGS. 4A to 4G are cross-sectional views sequentially showing anembodiment of a manufacturing method of a solar cell and a unit cell ofthe solar cell;

FIG. 5 is a cross-sectional view of another embodiment of a solar cell;and

FIGS. 6A to 6F are cross-sectional views sequentially showing anotherembodiment of a manufacturing method of the solar cell.

DETAILED DESCRIPTION

Embodiments now will be described more fully hereinafter with referenceto the accompanying drawings, in which embodiments of the invention areshown. The embodiments may, however, be embodied in many different formsand should not be construed as limited to the embodiments set forthherein. Rather, these embodiments are provided such that this disclosurewill be thorough and complete and will fully convey the scope of theinvention to those skilled in the art.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals refer to likeelements throughout the specification. It will be understood that whenan element such as a layer, film or substrate is referred to as being“on” another element, it may be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.

It will be understood that, although the terms “first,” “second,”“third” etc. may be used herein to describe various elements,components, regions, layers and/or sections, these elements, components,regions, layers and/or sections should not be limited by these terms.These terms are only used to distinguish one element, component, region,layer or section from another element, component, region, layer orsection. Thus, “a first element,” “component,” “region,” “layer” or“section” discussed below could be termed a second element, component,region, layer or section without departing from the teachings herein.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, theterms “a” and “an” are open terms that may be used in conjunction withsingular items or with plural items. It will be further understood thatthe terms “comprises” and/or “comprising,” or “includes” and/or“including” when used in this specification, specify the presence ofstated features, regions, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, regions, integers, steps, operations, elements,components, and/or groups thereof.

Furthermore, relative terms, such as “lower” or “bottom” and “upper” or“top,” may be used herein to describe one element's relationship toanother elements as illustrated in the Figures. It will be understoodthat relative terms are intended to encompass different orientations ofthe device in addition to the orientation depicted in the Figures. Forexample, if the device in one of the figures is turned over, elementsdescribed as being on the “lower” side of other elements would then beoriented on “upper” sides of the other elements. The exemplary term“lower,” can therefore, encompasses both an orientation of “lower” and“upper,” depending on the particular orientation of the figure.Similarly, if the device in one of the figures is turned over, elementsdescribed as “below” or “beneath” other elements would then be oriented“above” the other elements. The exemplary terms “below” or “beneath”can, therefore, encompass both an orientation of above and below.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure belongs. It willbe further understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art and thepresent disclosure, and will not be interpreted in an idealized oroverly formal sense unless expressly so defined herein.

Exemplary embodiments are described herein with reference to crosssection illustrations that are schematic illustrations of idealizedembodiments. As such, variations from the shapes of the illustrations asa result, for example, of manufacturing techniques and/or tolerances,are to be expected. Thus, embodiments described herein should not beconstrued as limited to the particular shapes of regions as illustratedherein but are to include deviations in shapes that result, for example,from manufacturing. For example, a region illustrated or described asflat may, typically, have rough and/or nonlinear features. Moreover,sharp angles that are illustrated may be rounded. Thus, the regionsillustrated in the figures are schematic in nature and their shapes arenot intended to illustrate the precise shape of a region and are notintended to limit the scope of the present claims.

According to one embodiment, the substrate includes a semiconductorlayer, a plurality of dielectric layers disposed on one side of thesemiconductor layer and separated from each other and a photoactivelayer disposed between the dielectric layers and including a compound ofa Group III element and a Group V element. Hereinafter, the substrateaccording to one embodiment is described in detail referring to FIG. 1.

FIG. 1 is a cross-sectional view of an embodiment of a substrate.

Hereinafter, a term “front side” refers to the side receiving solarenergy and a term “rear side” refers to the side opposite to the frontside. In addition, for better understanding and ease of description, theupper and lower positional relationship is described with respect to asemiconductor layer 11, but is not limited thereto.

A substrate 10 includes a semiconductor layer 11.

The semiconductor layer 11 may include Si, Ge or a combination thereof.In an embodiment, the semiconductor layer includes Si. The semiconductorlayer 11 is light and resistant to radiation and mechanical impact andthus may be formed thin with a large area. If the semiconductor layer 11is used in a solar cell, then mechanical properties of the solar cellmay be improved and output per unit area may be improved.

Although the semiconductor layer 11 doped with a p-type impurity isshown in FIG. 1, a semiconductor layer doped with an n-type impurity mayalso be used. The p-type impurity may include a Group III compound, suchas boron (B) and aluminum (Al), and the n-type impurity may include aGroup V compound, such as phosphorus (P).

If the semiconductor layer 11 is doped with the p-type impurity, thenholes separated from a photoactive layer may be effectively collected atthe electrode. Further, if the semiconductor layer 11 is doped with ann-type impurity, then electrons separated from the photoactive layer maybe effectively collected at the electrode.

A plurality of dielectric layers 13 that are separated from each otheris disposed on a front side of the semiconductor layer 11.

The structure of the dielectric layer 13 determines the width of aphotoactive layer 15 to be disposed, thus substantially relieving oreffectively preventing strain generation in the photoactive layer 15.The structure of the dielectric layer 13 may also effectively prevent anincrease in a number of defects when increasing a dimension of thephotoactive layer 15, thus substantially relieving or effectivelypreventing defect formation in the photoactive layer 15, particularly onthe surface of the photoactive layer 15. In addition, if a solar cellincludes the dielectric layer 13, then the solar cell may be separatedinto various unit cells without substantially damaging the photoactivelayer 15.

The dielectric layer 13 may include an oxide, a nitride, an oxynitrideor a combination thereof. In an embodiment, the oxide may includealuminum oxide (Al₂O₃), silicon oxide (SiO_(x)), titanium oxide (TiO₂ orTiO₄) or a combination thereof, but is not limited thereto. The nitridemay include aluminum nitride (AlN), silicon nitride (SiN_(x)), titaniumnitride (TiN) or a combination thereof, but is not limited thereto. Theoxynitride may include aluminum oxynitride (AlON), silicon oxynitride(SiON), titanium oxynitride (TiON) or a combination thereof, but is notlimited thereto.

The distance between the dielectric layers 13 may be about 1 millimeter(mm) to about 10 mm. If a distance between the dielectric layers 13 iswithin the above range, then strain generation in the photoactive layer15 may be effectively prevented or substantially relieved.

The dielectric layer 13 may have a thickness of about 1 micrometer (μm)to about 20 μm. If a thickness of the dielectric layer 13 is within theabove range, then the photoactive layer 15 may be easily disposed. Thethickness of the dielectric layer 13 is measured along a directionsubstantially perpendicular to a surface of the semiconductor layer 11.Further, in an embodiment, photoactive layers 15 existing symmetricallyto each other with respect to the dielectric layer 13 may be easilyseparated mechanically and electrically.

The dielectric layer 13 may have a width of about 1 μm to about 200 μm.If a width of the dielectric layer 13 is within the above range, then asolar cell including the dielectric layer 13 may be effectivelyseparated into unit cells without substantially damaging the photoactivelayer 15. The width of the dielectric layer 13 is measured along adirection substantially parallel to the surface of the semiconductorlayer 11.

The photoactive layer 15 includes a lower photoactive layer 15 a and anupper photoactive layer 15 b. The photoactive layer 15 is disposedbetween the dielectric layers 13 that are separated from each other. Thephotoactive layer 15 may include a compound of a Group III element and acompound of a Group V element. Group III includes elements such as boron(B), aluminum (Al), gallium (Ga), indium (In), thallium (Tl) or acombination thereof. Group V includes elements such as nitrogen (N),phosphorous (P), arsenic (As), antimony (Sb), bismuth (Bi) or acombination thereof.

One of the lower photoactive layer 15 a and the upper photoactive layer15 b may be doped with a p-type impurity and the other may be doped withan n-type impurity. The p-type impurity may include a Group II bcompound, such as zinc (Zn) and cadmium (Cd) and a Group III compound,such boron (B), or a combination thereof. The n-type impurity mayinclude a Group IV compound, such as silicon (Si) and a Group VIcompound, such as selenium (Se) and tellurium (Te), or a combinationthereof.

Although the lower photoactive layer 15 a doped with a p-type impurityand the upper photoactive layer 15 b doped with an n-type impurity areshown in FIG. 1, the lower photoactive layer 15 a may be doped with ann-type impurity and the upper photoactive layer 15 b may be doped with ap-type impurity.

The thickness of the photoactive layer 15 may be equal to or less thanthe thickness of the dielectric layer 13. The thickness of thephotoactive layer 15 is measured along the direction substantiallyperpendicular to the surface of the semiconductor layer 11. Thus, straingeneration in the photoactive layer 15 may be effectively prevented orsubstantially relieved. Further, when a solar cell including thedielectric layer 13 is separated into unit cells by vertically cuttingthe dielectric layer 13, the solar cell may be effectively separatedwithout substantially damaging the photoactive layer 15.

The substrate 10 may further include at least one of auxiliary layers13′ disposed on one side of the semiconductor layer 11. In anembodiment, auxiliary layers 13′ are covered with the photoactive layer15 and are separated from each other. Although many auxiliary layers 13′are shown in FIG. 1, an embodiment of the substrate 10 may not includethe auxiliary layers 13′.

If the substrate 10 includes the auxiliary layers 13′, then an increasein a number of defects may be effectively prevented when increasing thedimension of the photoactive layer 15. The inclusion of the auxiliarylayers 13′ thus effectively prevents or substantially relieves defectformation in the photoactive layer 15, particularly on the surface ofthe photoactive layer 15. The inclusion of the auxiliary layers 13′further effectively prevents or substantially relieves strain generationin the photoactive layer 15.

The auxiliary layer 13′ may include an oxide, a nitride, an oxynitrideor a combination thereof. Hereinafter, unless otherwise indicated, theoxide, the nitride and the oxynitride are as described above.

The distance between the auxiliary layers 13′ may be about 10 nanometers(nm) to about 1 μm. If a distance between the auxiliary layers 13′ iswithin the above range, then defect formation in the photoactive layer15 may be effectively prevented or substantially relieved when disposingthe photoactive layer 15.

A thickness of the auxiliary layer 13′ is less than the thickness of thedielectric layer 13 and the thickness of the auxiliary layer 13′ may beabout 1 nm to about 100 nm. The thickness of the auxiliary layer 13′ ismeasured along the direction substantially perpendicular to the surfaceof the semiconductor layer 11. If a thickness of the auxiliary layer 13′is within the above range, then defect formation in the photoactivelayer 15 may be effectively prevented or substantially relieved whendisposing the photoactive layer 15.

The auxiliary layer 13′ may have a width of about 1 nm to about 100 nm.The width of the auxiliary layer 13′ is measured along the directionsubstantially parallel to the surface of the semiconductor layer 11. Ifa width of the auxiliary layer 13′ is within the above range, then, whendisposing the photoactive layer 15, defect formation in the photoactivelayer 15 may be effectively prevented or substantially relieved.

An embodiment of a method for manufacturing a substrate includes forminga semiconductor layer, forming a plurality of dielectric layersseparated from each other on one side of the semiconductor layer andforming a photoactive layer including a compound of a Group III elementand a Group V element between the dielectric layers. Referring to FIGS.2A to 2D together with FIG. 1, an embodiment of a manufacturing methodof a substrate is described in detail referring to FIGS. 2A to 2Dtogether with FIG. 1.

FIGS. 2A to 2D are cross-sectional views sequentially showing anembodiment of a manufacturing method of a substrate.

First, referring to FIG. 2A, a semiconductor layer 11 is formed. Thesemiconductor layer 11 may be formed as a silicon wafer. Thesemiconductor layer 11 may be doped with, for example, a p-typeimpurity, or doped with an n-type impurity.

Next, referring to FIG. 2B, a patterned dielectric layer 13 is formed ona front side of the semiconductor layer 11. The patterned dielectriclayer 13 may be formed on the front side of the semiconductor layer 11by applying, for example, silicon nitride by Plasma Enhanced ChemicalVapor Deposition (“PECVD”) and then etching using a photoresist topattern the dielectric layer 13, or by screen printing, inkjet printing,press printing or a combination thereof, but not limited thereto.

The dielectric layers 13 may be formed so as to have a distancetherebetween of about 1 mm to about 10 mm, a thickness of about 1 μm toabout 20 μm and a width of about 1 μm to about 200 μm.

Next, referring to FIG. 2C, a patterned auxiliary layer 13′distinguished from the dielectric layer 13 is formed on the front sideof the semiconductor layer 11. The patterned auxiliary layer 13′ may beformed similarly to the patterned dielectric layer 13. Although aprocess for forming the patterned auxiliary layer 13′ is shown in FIG.2C, in an embodiment, the process may be omitted.

The auxiliary layer 13′ may be formed such that the thickness of theauxiliary layer 13′ may be less than the thickness of the dielectriclayer 13.

Next, referring to FIG. 2D, a photoactive layer 15 is formed between thedielectric layers 13 so as to cover the auxiliary layer 13′.

In an embodiment, by sequentially growing Zn-doped GaAs and Si-dopedGaAs by a Metal-Organic Vapor Phase Epitaxy (“MOVPE”), a Molecular BeamEpitaxy (“MBE”), or a Chemical Beam Epitaxy (“CBE”), the photoactivelayer 15 including a lower photoactive layer 15 a doped with a p-typeimpurity and an upper photoactive layer 15 b doped with an n-typeimpurity may be formed. However, the lower photoactive layer 15 a may bedoped with an n-type impurity and the upper photoactive layer 15 b maybe doped with a p-type impurity.

The photoactive layer 15 may be formed such that the thickness of thephotoactive layer 15 may be equal to or less than the thickness of thedielectric layer 13.

As previously described, if a plurality of dielectric layers 13 areformed on the front side of the semiconductor layer 11 and then thephotoactive layer 15 is formed between the dielectric layers 13, thendefect and strain generation in the photoactive layer 15 may beeffectively prevented or substantially relieved.

An embodiment of a solar cell includes a semiconductor layer, aplurality of dielectric layers disposed on one side of the semiconductorlayer and separated from each other, a photoactive layer disposedbetween the dielectric layers and including a compound of a Group IIIelement and a Group V element, a first electrode electrically connectedto the semiconductor layer and a second electrode electrically connectedto the photoactive layer.

The second electrode may be disposed on one side of the dielectriclayer, on one side of the photoactive layer or on both.

The structure of the solar cell may determine the width of a photoactivelayer to be disposed by inclusion of the dielectric layer, thuseffectively preventing or substantially relieving strain generation inthe photoactive layer. Further, when dimensions of the photoactive layerare increased and the photoactive layer is disposed, then an increase inthe number of defects may be substantially blocked to effectivelyprevent or substantially relieve defect formation in the photoactivelayer, particularly on the surface of the photoactive layer.

An embodiment of a manufacturing method of a solar cell includes forminga semiconductor layer, forming a plurality of dielectric layersseparated from each other on one side of the semiconductor layer,forming a photoactive layer including a compound of a Group III elementand a Group V element between the dielectric layers, disposing a firstelectrode electrically connected to the semiconductor layer anddisposing a second electrode electrically connected to the photoactivelayer.

Referring to FIG. 3A, an embodiment of a solar cell is described. FIG.3A is a cross-sectional view of an embodiment of a solar cell.

A solar cell 100 includes a semiconductor layer 110. Hereinafter, unlessotherwise indicated, the semiconductor layer 110 is as described above.

On a front side of the semiconductor layer 110, a plurality ofdielectric layers 130 separated from each other are disposed.Hereinafter, unless otherwise indicated, the dielectric layers 130 areas described above.

The distance between the dielectric layers 130 may be about 1 mm toabout 10 mm. If the distance between the dielectric layers 130 is withinthe above range, then strain generation in the photoactive layer 150 maybe effectively prevented or substantially relieved. In an embodiment,the distance between the dielectric layers 130 may be about 1 mm toabout 7 mm. In an embodiment, the distance between the dielectric layers130 may be about 3 mm to about 7 mm.

The dielectric layer 130 may have a thickness of about 1 μm to about 20μm. If the thickness of the dielectric layer 130 is within the aboverange, then the photoactive layer 150 may be easily disposed. Further,in an embodiment, photoactive layers 150 existing symmetrically to eachother with respect to the dielectric layer 130 may be easily separatedmechanically and electrically.

The dielectric layer 130 may have a width of about 1 μm to about 200 μm.If the width of the dielectric layer 130 is within the above range, thenthe solar cell 100 may be effectively separated into unit cells withoutsubstantially damaging the photoactive layer 150. In an embodiment, thedielectric layer 130 may have a width of about 10 μm to about 200 μm. Inanother embodiment, the dielectric layer 130 may have a width of about10 μm to about 100 μm. In yet another embodiment, the dielectric layer130 may have a width of about 30 μm to about 100 μm.

The photoactive layer 150 including a lower photoactive layer 150 a andan upper photoactive layer 150 b is disposed between the dielectriclayers 130 that are separated from each other. Hereinafter, unlessotherwise indicated, the photoactive layer 150, the lower photoactivelayer 150 a and the upper photoactive layer 150 b are as describedabove.

A front electrode 190 is disposed on the photoactive layer 150. In anembodiment, a plurality of front electrodes 190 that are separated fromeach other may be disposed on one photoactive layer 150.

The front electrode 190 may be made of a low resistance metal, such asmolybdenum (Mo), aluminum (Al), silver (Ag), gold (Au), platinum (Pt),nickel (Ni) and copper (Cu). The front electrode 190 may be designed ina grid pattern considering shadowing loss and sheet resistance.

In an embodiment, the front electrode 190 may include a transparentconductive material that transmits solar light and has conductivity. Thetransparent conductive material may include a transparent conductiveoxide (“TCO”), such as ZnO:Al, ZnO:B, SnO₂, SnO₂:F or indium tin oxide(“ITO”), which often effectively prevents deterioration of lighttransmittance and has low resistivity and good surface roughness.

A rear electrode 170 is disposed under the semiconductor layer 110.

The rear electrode 170 may reflect light passing through thesemiconductor layer 110 back to the semiconductor layer 110, therebyeffectively preventing light loss to increase solar cell efficiency.

The rear electrode 170 may be made of, for example, molybdenum (Mo),aluminum (Al), silver (Ag), gold (Au), platinum (Pt), nickel (Ni),copper (Cu) or a combination thereof.

The solar cell 100 may further include at least one of auxiliary layers131 disposed on one side of the semiconductor layer, covered with thephotoactive layer 150 and separated from each other. Although theauxiliary layers 131 are shown in FIG. 3A, an embodiment of the solarcell 100 may not include the auxiliary layers 131. Hereinafter, unlessotherwise indicated, the auxiliary layers 131 are as described above.

The distance between the auxiliary layers 131 may be about 10 nm toabout 1 μm. If the distance between the auxiliary layers 131 is withinthe above range, then defect formation in the photoactive layer 150 maybe effectively prevented or substantially relieved when disposing thephotoactive layer 150. In an embodiment, the distance between theauxiliary layers 131 may be about 100 nm to about 1 μm.

The thickness of the auxiliary layer 131 is less than the thickness ofthe dielectric layer 130. The thickness of the auxiliary layer 131 maybe about 1 nm to about 100 nm. If the thickness of the auxiliary layer131 is within the above range, then, when disposing the photoactivelayer 150, defect formation in the photoactive layer 150 may beeffectively prevented or substantially relieved. In an embodiment, theauxiliary layer 131 may have a thickness of about 10 nm to about 100 nm.

The auxiliary layer 131 may have a width of about 1 nm to about 100 nm.If the width of the auxiliary layer 131 is within the above range, then,when disposing the photoactive layer 150, defect formation in thephotoactive layer 150 may be effectively prevented or substantiallyrelieved. In an embodiment, the auxiliary layer 131 may have a width ofabout 10 nm to about 100 nm.

The solar cell 100 may be separated into a plurality of unit cells 100′by cutting the dielectric layer 130, the semiconductor layer 110 and therear electrode 170 along the vertical direction of the dielectric layer130. FIG. 3B is a cross-sectional view of an embodiment of a unit cell100′ of the separated solar cell.

Referring to FIGS. 4A to 4G together with FIG. 3A and FIG. 3B, anembodiment of a manufacturing method of a solar cell 100 and a unit cell100′ of the solar cell is described. FIGS. 4A to 4G are cross-sectionalviews sequentially showing an embodiment of a manufacturing method ofthe solar cell 100 and the unit cell 100′ of the solar cell.

First, referring to FIG. 4A, a semiconductor layer 110 is formed.Hereinafter, unless otherwise indicated, the semiconductor layer 110 isas described above.

Next, referring to FIG. 4B, a plurality of patterned dielectric layers130 is formed on a front side of the semiconductor layer 110. Theformation of the plurality of patterned dielectric layers 130 is asdescribed above.

Next, referring to FIG. 4C, a plurality of auxiliary layers 131distinguished from the dielectric layer 130 is formed on the front sideof the semiconductor layer 110. The formation of the plurality of thepatterned auxiliary layers 131 is as described in the formation of thepatterned dielectric layer.

Although a process for forming the patterned auxiliary layer 131 isshown in FIG. 4C, in an embodiment, the process may be omitted.

Next, referring to FIG. 4D, a photoactive layer 150 including a lowerphotoactive layer 150 a and an upper photoactive layer 150 b is formedbetween the dielectric layers 130 so as to cover the auxiliary layer131. The formation of the photoactive layer 150 is as described above.

Next, referring to FIG. 4E, a rear electrode 170 is disposed on the rearside of the semiconductor layer 110. The rear electrode 170 may bemanufactured using a material having excellent conductivity, such assilver (Ag), gold (Au), by sputtering, vacuum deposition or acombination thereof.

Next, referring to FIG. 4F, a front electrode 190 is disposed on a frontside of the photoactive layer 150. The front electrode 190 may bemanufactured using a material having excellent conductivity, such as Ag,Au, by screen-printing, inkjet printing, press printing or a combinationthereof. In an embodiment, a plurality of the front electrodes 190 maybe disposed so as to be separate from each other on the front side ofthe photoactive layer 150.

Next, referring to FIG. 4G, the solar cell may be separated into a unitcell 100′ by cutting the dielectric layer 130, the semiconductor layer110 and the rear electrode 170 along the vertical direction of thedielectric layer 130. To separate the solar cell 100 into a unit cell100′, a cutting method using a sawing machine may be used, but is notlimited thereto. Since the solar cell 100 may be separated into the unitcell 100′ without damaging the photoactive layer 150, a further sidewalletching process may not be required, thus simplifying the manufacturingprocess. Thereby, performance and economics of the manufacturing methodof the solar cell 100 may be improved. Although a process for separatingthe solar cell 100 into the unit cell 100′ is shown in FIG. 4G, in anembodiment, the process may be omitted.

Referring to FIG. 5, an embodiment of a solar cell is described. FIG. 5is a cross-sectional view of an embodiment of a solar cell.

A solar cell 200 includes a semiconductor layer 210. A plurality ofdielectric layers 230 that are separated from each other is disposed ona front side of the semiconductor layer 210. A photoactive layer 250including a lower photoactive layer 250 a and an upper photoactive layer250 b is disposed between the dielectric layers 230. A front electrode290 is disposed on the dielectric layer 230. A rear electrode 270 isdisposed under the semiconductor layer 210. The solar cell 200 mayfurther include at least one of auxiliary layers 231 formed on one sideof the semiconductor layer 210, covered with the photoactive layer 250and separated from each other.

Hereinafter, unless otherwise indicated, the semiconductor layer 210,the dielectric layer 231, the photoactive layer 250, the front electrode290, the rear electrode 270 and the auxiliary layer 231 are as describedabove.

The distance between the dielectric layers 230 may be about 1 mm toabout 10 mm. If the distance between the dielectric layers 230 is withinthe above range, then strain generation in the photoactive layer 250 maybe effectively prevented or substantially relieved. In an embodiment,the distance between the dielectric layers 230 may be about 3 mm toabout 10 mm. In an embodiment, the distance between the dielectriclayers 230 may be about 5 mm to about 10 mm.

The dielectric layer 230 may have a width of about 1 μm to about 200 μm.If the width of the dielectric layer 230 is within the above range, thenstrain generation in the photoactive layer 250 may be effectivelyprevented or substantially relieved. Additionally, subsequentlydescribed generation of a dark current under the front electrode 290 maybe effectively prevented or effectively decreased. In an embodiment, thedielectric layer 230 may have a width of about 1 μm to about 100 μm. Inan embodiment, the dielectric layer 230 may have a width of about 5 μmto about 50 μm.

The front electrode 290 is disposed on the dielectric layer 230. Thewidth of the front electrode 290 may be larger than the width of thedielectric layer 230. Thus, the generation of the dark current in thefront electrode 290 may be suppressed to increase the open circuitvoltage (Voc).

The solar cell 200 may further include at least one of auxiliary layers231 disposed on one side of the semiconductor layer 210, covered withthe photoactive layer 250 and separated from each other. Although theauxiliary layers 231 are shown in FIG. 4, in an embodiment, the solarcell 200 may not include the auxiliary layers 231.

Referring to FIGS. 6A to 6F together with FIG. 5, an embodiment of amanufacturing method of a solar cell 200 is described. FIGS. 6A to 6Fare cross-sectional view sequentially showing an embodiment of amanufacturing method of the solar cell 200.

First, referring to FIG. 6A, a semiconductor layer 210 is formed.Hereinafter, unless otherwise indicated, the semiconductor layer 210 isas described above.

Next, referring to FIG. 6B, a plurality of patterned dielectric layers230 is formed on the front side of the semiconductor layer 210. Theformation of the patterned dielectric layers 230 is as described above.

Next, referring to FIG. 6C, a patterned auxiliary layer 231,distinguished from the dielectric layer 230, is formed on the front sideof the semiconductor layer 210. The formation of the patterned auxiliarylayer 231 is as described above. Although a process for forming thepatterned auxiliary layer 231 is shown in FIG. 6C, in an embodiment, theprocess may be omitted.

Next, referring to FIG. 6D, a photoactive layer 250 is formed betweenthe dielectric layers 230 separated from each other so as to cover theauxiliary layer 231. The formation of the photoactive layer 250 is asdescribed above. Next, referring to FIG. 6E, a rear electrode 270 isdisposed on the rear side of the semiconductor layer 210. Thedisposition of the rear electrode 270 is as described above.

Next, referring to FIG. 6F, a front electrode 290 is disposed on thefront side of the dielectric layer 230. The structure of the frontelectrode 290 may be such that width of the front electrode 290 may belarger than the width of the dielectric layer 230.

The disposition of the front electrode 290 is as described above.

As described, if the plurality of dielectric layers 230 are disposed onthe front side of the semiconductor layer 210 and then the photoactivelayer 250 is formed between the dielectric layers 230, then defect andstrain generation in the photoactive layer 250 may be effectivelyprevented or substantially relieved.

While this disclosure has been described in connection with what ispresently considered to be practical embodiments, a skilled artisanunderstands that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. A substrate comprising: a semiconductor layer; aplurality of dielectric layers disposed on one side of the semiconductorlayer, which defines a plurality of unit cells; a plurality of auxiliarylayers disposed on the one side of the semiconductor layer; and aphotoactive layer disposed between the dielectric layers, covering theplurality of auxiliary layers and comprising a compound of a Group IIIelement and a Group V element, wherein each unit cell includes anauxiliary layer of the plurality of auxiliary layers, and a thickness ofeach auxiliary layer of the plurality of auxiliary layers is less than athickness of each dielectric layer of the plurality of dielectriclayers.
 2. The substrate of claim 1, wherein the semiconductor layercomprises at least one of Si, Ge and a combination thereof.
 3. Thesubstrate of claim 2, wherein the semiconductor layer comprises Si. 4.The substrate of claim 1, wherein the each dielectric layer comprises atleast one of an oxide, a nitride, an oxynitride, and a combinationthereof, and the oxide comprises at least one of aluminum oxide (Al₂O₃),silicon oxide (SiO_(x)), titanium oxide (TiO₂ or TiO₄), and acombination thereof, the nitride comprises at least one of aluminumnitride (AlN), silicon nitride (SiN_(x)), titanium nitride (TiN), and acombination thereof, and the oxynitride comprises at least one ofaluminum oxynitride (AlON), silicon oxynitride (SiON), titaniumoxynitride (TiON), and a combination thereof.
 5. The substrate of claim1, wherein a distance between two adjacent dielectric layers of theplurality of dielectric layers is from about 1 millimeter to about 10millimeters.
 6. The substrate of claim 1, wherein the thickness of theeach dielectric layer is from about 1 micrometer to about 20micrometers.
 7. The substrate of claim 1, wherein a width of the eachdielectric layer is from about 1 micrometer to about 200 micrometers. 8.The substrate of claim 1, wherein the Group III element comprises atleast one of B, Al, Ga, In, Tl and a combination thereof.
 9. Thesubstrate of claim 1, wherein the Group V element comprises at least oneof N, P, As, Sb, Bi and a combination thereof.
 10. The substrate ofclaim 1, wherein a thickness of the photoactive layer is equal to orless than the thickness of the each dielectric layer.
 11. The substrateof claim 1, wherein the each auxiliary layer comprises at least one ofan oxide, a nitride, an oxynitride, or a combination thereof, and theoxide comprises at least one of aluminum oxide (Al₂O₃), silicon oxide(SiO_(x)), titanium oxide (TiO₂ or TiO₄), or a combination thereof, thenitride comprises at least one of aluminum nitride (AlN), siliconnitride (SiN_(x)), titanium nitride (TiN), or a combination thereof, andthe oxynitride comprises at least one of aluminum oxynitride (AlON),silicon oxynitride (SiON), titanium oxynitride (TiON), or a combinationthereof.
 12. The substrate of claim 1, the each unit cell comprises twoor more auxiliary layers which are separated from each other, wherein adistance between two adjacent auxiliary layers of the two or moreauxiliary layers is from about 10 nanometers to about 1 micrometer. 13.The substrate of claim 1, wherein the thickness of the each auxiliarylayer is from about 1 nanometer to about 100 nanometers.
 14. Thesubstrate of claim 1, wherein a width of the each auxiliary layer isfrom about 1 nanometer to about 100 nanometers.
 15. A solar cellcomprising: a semiconductor layer; a plurality of dielectric layersdisposed on one side of the semiconductor layer, which defines aplurality of unit cells; a plurality of auxiliary layers disposed on theone side of the semiconductor layer; and a photoactive layer disposedbetween the dielectric layers, covering the plurality of auxiliarylayers and comprising a compound of a Group III element and a Group Velement; a first electrode electrically connected to the semiconductorlayer; and a second electrode electrically connected to the photoactivelayer, wherein each unit cell includes an auxiliary layer of theplurality of auxiliary layers, and a thickness of each auxiliary layerof the plurality of auxiliary layers is less than a thickness of eachdielectric layer of the plurality of dielectric layers.
 16. The solarcell of claim 15, wherein the semiconductor layer comprises at least oneof Si, Ge and a combination thereof.
 17. The solar cell of claim 16,wherein the semiconductor layer comprises Si.
 18. The solar cell ofclaim 15, wherein the each dielectric layer comprises at least one of anoxide, a nitride, an oxynitride, and a combination thereof, and theoxide comprises at least one of aluminum oxide (Al₂O₃), silicon oxide(SiO_(x)), titanium oxide (TiO₂ or TiO₄), and a combination thereof, thenitride comprises at least one of aluminum nitride (AlN), siliconnitride (SiN_(x)), titanium nitride (TiN), and a combination thereof,and the oxynitride comprises at least one of aluminum oxynitride (AlON),silicon oxynitride (SiON), titanium oxynitride (TiON), and a combinationthereof.
 19. The solar cell of claim 15, wherein a distance between twoadjacent dielectric layers of the plurality of dielectric layers is fromabout 1 millimeter to about 10 millimeters.
 20. The solar cell of claim15, wherein the thickness of the each dielectric layer is from about 1micrometer to about 20 micrometers.
 21. The solar cell of claim 15,wherein a width of the each dielectric layer is from about 1 micrometerto about 200 micrometers.
 22. The solar cell of claim 15, wherein theGroup III element comprises at least one of B, Al, Ga, In, Tl and acombination thereof.
 23. The solar cell of claim 15, wherein the Group Velement comprises at least one of N, P, As, Sb, Bi and a combinationthereof.
 24. The solar cell of claim 15, wherein a thickness of thephotoactive layer is equal to or less than the thickness of the eachdielectric layer.
 25. The solar cell of claim 15, wherein the secondelectrode is disposed on one side of the each dielectric layer, on oneside of the photoactive layer, or on both.
 26. The solar cell of claim25, wherein a width of the second electrode is larger than a width ofthe each dielectric layer s when the second electrode is disposed on theone side of the each dielectric layer.
 27. The solar cell of claim 15,wherein the each auxiliary layer comprises at least one of an oxide, anitride, an oxynitride, and a combination thereof, and the oxidecomprises at least one of aluminum oxide (Al₂O₃), silicon oxide(SiO_(x)), titanium oxide (TiO₂ or TiO₄), and a combination thereof, thenitride comprises at least one of aluminum nitride (AlN), siliconnitride (SiN_(x)), titanium nitride (TiN), and a combination thereof,and the oxynitride comprises at least one of aluminum oxynitride (AlON),silicon oxynitride (SiON), titanium oxynitride (TiON), and a combinationthereof.
 28. The solar cell of claim 15, each the unit cell comprisestwo or more auxiliary layers separated from each other, wherein adistance between two adjacent auxiliary layers of the two or moreauxiliary layers is from about 10 nanometers to about 1 micrometer, andthe thickness of the each auxiliary layer is from about 1 nanometer toabout 100 nanometers, and a width of the each auxiliary layer is fromabout 1 nanometer to about 100 nanometers.